The present invention relates to a method for insert molding a contact module, and particularly to a method for insert molding a contact module having at least two rows of high density contacts.
As the technology of communication networks and portable computers progresses, the exchange of information between different electronic instruments is increased. The miniaturization trend of computers limits the inner space of a computer and increases the density of inner components thereof. Thus, electrical connectors used for transmitting signals in the computer require a large quantity of electrical contacts arranged in a high density.
In conventional methods for manufacturing an electrical connector, as disclosed in Taiwan Patent Application Nos. 77208350, 79204276, 80209366 and 80213361, an inserting method is adopted to insert rows of contacts at appropriate positions in a housing of a connector. The contacts are then forced into the housing.
Referring to FIG. 1, a contact carrier strip 100 and an insulative housing 200 are manufactured by means of stamping and injection molding, respectively. The strip 100 includes a number of contacts 101. The housing 200 defines several rows of contact passageways 300. The contacts 101 are then forced into the contact passageways 300.
However, such an inserting method will damage the mechanical and electrical performance of the connector. The contact passageways of the housing are required to be increased in quantity as well as density. Side walls of the contact passageways with a uniform thickness becomes difficult. In addition, since the contacts interferentially engage with the side walls of the contact passageways, the contacts may wear away surfaces of the sidewallls thereby failing to effectively insulate the contacts from each other and adversely affecting signal transmission through the electrical connector. Furthermore, as surface mount technology (SMT) is commonly employed for attaching a large number of contacts to a circuit board with a high density, the contacts must exhibit good coplanarity for achieving a good electrical connection after soldering operation. However, soldering ends of the contacts will inevitably deform thereby disrupting coplanarity and adversely affecting the performance of the connector.
In order to overcome the deficiencies of the inserting method, one or more insulative inserting bases are employed to ensure the planarity of contacts of an electrical connector. Referring to U.S. Pat. No. 4,775,333 as shown in FIG. 2, the method first forms a plurality of electrical contact elements 400 and then positions the contact elements 400 into a mold for insert molding an insulative carrier element 500 and an insulative support base 550 therearound to form a module 600. The module 600 is then assembled into an electrical connector. Such a method can effectively overcome the disadvantages of the inserting method. However, due to the demand of a high density of electrical connectors, contacts containing carrier strips are no longer formed in only one row but many rows in a vertically overlapping relationship thereby complicating assembly. Thus, the simple insert molding mode of one row of contacts can not meet current requirements.
Further referring to U.S. Pat. No. 5,274,918, a method is adopted for manufacturing a shorting bar insert for placement in a modular jack assembly to provide for the selective shorting of predetermined contacts during periods of non-electrical engagement with a modular plug. However, the selective shorting of the contacts limits the type and amount of the contacts. In addition, the back-to-back arrangement of contact carrier strips is not suitable for contacts of many other types of electrical connectors.